I thought they were an option. The ones I have seen were not like the little 'donuts' of today. They were more of a full size rim, but the tire had special sidewalls that kept the tire tight to the rim when uninflated. My dad's 78 Chevy came with one... it was very compact. Not much more space consuming than if you had a stock rim, less tire, in the back. Then there was a little pressure canister that held just enough air to inflate the tire when needed. I know Fords from the 70s had the same setup, as an extra cost option. I would be lying if I said I could remember the Mav being one of those cars.
I have never seen a Mav or Comet with one, but would not say they never were offered, cuz I simply dont know. I have one in my 79 Z-28 with the filler can, never has been out of the trunk. The wheel appears to be 15" with a razor appearing tire. Dan ps you have to remember, after 30+ years, things get changed, and stuff gets tossed in the trunk, like different spare tires.
Here's a 70 Stang space saver. They are funny because there is stock rim, and it is wrapped with tread... but there is no sidewall. Then you plug the canister in and the sidewall unfolds. When it's all over, it looks just like any other tire on the car EXCEPT the SS looks like a bias ply when inflated. Not a radial.
They were an option on the big bumper cars ... It would be a neat option for a show car ... but impractical for a daily driver for which I would want a real spare .. since I wouldn't trust a 30 year old space saver to even hold air.
I know if they came on a Mustang or Cougar, the mount welded to the floor was different. We drove 6 hrs to get one for my buddys AMX.
